They are the same drive, but one uses a 50 pin interface and one is 68. The Ultra Wide is 68, and yeah the other is just Ultra but it doesn't matter. Basically the 50 pin (Ultraplex 40X Max) version is the regular version and is the one you should get. They perform the same, but some would say the Max version performs better due to more firmware updates, though I doubt the difference could be much at all. Great drive, I have one myself, very nice. Just buy the 50 pin Max version, it's cheaper.